Abstract: The present report deals with the stereospecific synthesis of the O, O-dimethyl-O-(1-ethoxycarbonyl-1-propen-2-yl) phosphate, an insecticide named Mie-Ya-jing in Chinese. The reaction of phosphorus oxychloride with ethyl acetoacetate in the presence of tributylamine yeilded specifically the E-stereoisomer as the key intermediate, from which E-stereoisomer "Mie-Ya-jing" was prepared by treating with excess of methyl alcohol. It seems that there is a relationship between the steric factors of the base and the E/Zratio obtained. The Z-stereoisomer was synthesized by the action of dimethyl phosphoryl Chloride on ethyl sodioacetoacetate. The other two Mie-Ya-jing derivatives were similarly prepared. The E-isomer proved to be more toxic to insects than the corresponding Z-isomers.